Multimedia streaming is considered to be a major evolving Internet application since it aims at replacing widely known television applications such as video-on-demand, pay-per-view, or video broadcast. Currently, a number of portal sites offer Internet protocol (IP) multicast services to be extended transmission to wireless terminals. With such a service, a wireless system broadcasts data packets to a plurality of wireless terminals. Each wireless terminal receives and processes the same stream of packets. Using multicast transmission rather than a plurality of unicast transmissions is substantially more spectrum efficient providing that the services are amenable to broadcasting to the plurality of wireless terminals. Because frequency spectrum for wireless services is very limited and very expensive to expand, the utilization of multicast services is very appealing to wireless service providers.
An example of a multicast service is IP multicast streaming for news and entertainment content in audio and video formats. As the data rate of wireless channels continues to increase and as the wireless channels are becoming optimized for IP packet transfers as with cdma2000 1.25 MHz Evolution (1×EV) 3GPP2 wireless standards, an increasing number of wireless customers will have access to multicast services. If the service were provided with a dedicated communications link between a base station and each wireless terminal in the same geographical area (corresponding to a cell that is served by the base station), the frequency spectrum usage essentially increases proportionally to the number of wireless terminals that subscribe to the service. This approach is not efficient in that data transmission is duplicated for the participating wireless terminals. Multicast services broadcast the data stream to all the participating wireless terminals on the wireless downlink (base station to wireless terminals), eliminating the duplication of data transmission and thus improving the frequency spectrum efficiency of the wireless channels.
Typically, multicast services are inherently unidirectional from the wireless base station to the wireless terminal. As an example, a video service may require a transmission rate of several hundred thousand bits per second in the forward direction and several hundred bits per second in the reverse direction in order to support signaling. Because of the pronounced asymmetry of transmission, the quality of the received signal at the wireless terminal is an important parameter in supporting multicast services.